Bank Credit Agreements and Other Short-Term and Long-Term Debt - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Line Of Credit Facility [Line Items]
Long-term debt	$ 270,083,000	$ 429,841,000
Term Loan
Line Of Credit Facility [Line Items]
Long-term debt	165,800,000
U.S. Credit Facility
Line Of Credit Facility [Line Items]
Lines of credit maximum borrowing capacity	250,000,000
Long-term debt	$ 268,800,000
Line of credit facility, maturity date	Oct. 26, 2021
U.S. Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Line of credit facility increase in borrowing capacity	$ 200,000,000
U.S. Credit Facility | Final Year
Line Of Credit Facility [Line Items]
Debt instrument, quarterly periodic payment	9,400,000
U.S. Credit Facility | Term Loan
Line Of Credit Facility [Line Items]
Lines of credit maximum borrowing capacity	250,000,000
U.S. Credit Facility | Term Loan | 2016
Line Of Credit Facility [Line Items]
Debt instrument, quarterly periodic payment	3,100,000
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Long-term debt	103,000,000
Short-Term Debt
Line Of Credit Facility [Line Items]
Lines of credit unused and available	78,700,000
Line of credit facility advanced under foreign credit line	1,000,000
Line of Credit Facility Credit Used For Guarantee	900,000
Short-Term Debt | Unsecured
Line Of Credit Facility [Line Items]
Lines of credit maximum borrowing capacity	$ 80,500,000